


After Hours

by UntoldMuse



Category: Undertale (Video Game)
Genre: Angst, M/M, Marriage Proposal, Smut, Unrequited Love
Language: English
Status: Completed
Published: 2020-08-17
Updated: 2020-08-17
Packaged: 2021-03-06 03:28:08
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,089
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/25962844
Author URL: https://archiveofourown.org/users/UntoldMuse/pseuds/UntoldMuse
Summary: Gaster and Grillby are friends with benefits...A lot of benefits.But Grillby wants there to be more than just friendship between them.And in the tangle of sheets and desires, everyone is left wanting.
Relationships: Mentioned Asgore/Gaster, W. D. Gaster/Grillby
Kudos: 26





	After Hours

**Author's Note:**

> LISTEN this is an old draft that I just re-read and thought "eyyy I should post this" so I fixed it up and here we are. Enjoy~

It was a quiet Friday night. Only a couple of patrons milling around at _Grillby’s._ The restaurant’s owner, Grillby himself, was occupied cleaning glasses behind the bar. Nobody in Snowdin could figure out exactly _how_ he could “wash” dishes without touching water, but nevertheless they always came out spotless and clean. Grillby took a few shot glasses and placed them back in their box on the shelf. He liked to keep them in there, so they wouldn’t get lost or fall off the shelf.

As he turned back to clean a few more glasses, the door bell rang, signaling a new patron. “Welcome to Grillby’s-“ He began to say in a well-practiced voice. But then the bartender looked up at the new patron and smiled. “Gaster, you’re here early.” He said with a smirk on his face.

Gaster ambled over to the bar, taking a seat on one of the stools. “I got Sans and Papyrus started on their own little movie night. They’ve been watching human movies from the dump for hours.” Gaster replied. He shucked off his long, black overcoat, he’d been wearing outside in the snow. It was nice and toasty in the bar, and he didn’t need it.

“Fuku is staying at her friend’s house-“ Grillby mentioned. “I can close the bar in…hmm…10 minutes? If you wanna wait upstairs…” Gaster flashed a small grin, before getting off the barstool. Carrying his coat, he headed towards the door behind the bar.

“Don’t keep me waiting too long.” He said before disappearing through the door. That door immediately led to the kitchen, where Grillby cooked food for the customers, and a set of stairs that led to Grillby’s loft up above. Gaster went into the loft, turning on the lights. The whole room was flooded with a soft light, and Gaster laid his coat down on Grillby’s armchair. Then the skeleton took off his shoes, plodding on the old wooden floor over to the bed.

* * *

A few minutes later, Grillby came upstairs as well. All the bar patrons were gone, leaving the two monsters entirely to themselves. The fire elemental found Gaster laying on his bed, curled up under the sheets. “I mean I guess we could just _actually sleep_ together, but I was hoping for the other kind of “sleeping” to be honest.” Grillby commented.

Gaster sat up, chuckling at Grillby. “I was just relishing having a quiet moment and peaceful bed to myself…that never happens at home.” Gaster replied. Grillby nodded, he completely understood. Having two kids, and one being a newly-weaned teenager? No wonder Gaster was tired. “Anyway, I wouldn’t have come over here just to appreciate your mattress,” the skeleton said. “Take off that vest, or I will.”

Grillby growled excitedly, unbuttoning his black vest with lightning speed. He climbed onto the bed, crawling close to Gaster. “Now the shirt.” Gaster demanded.

“Since when did you get to be in charge?” Grillby asked incredulously.

“Since now.” Replied Gaster.

Grillby was taken aback, but he had to admit, seeing Gaster take a more dominant stance in the bedroom was pretty hot. His hands travelled up to the top of his shirt, unbuttoning it before he slipped it off his broad shoulders. Gaster blatantly stared at the fire elemental’s incredible chest. Grillby knew that Gaster had a thing for men with muscular chests and big arms, so he’d been secretly working out for the past few weeks, trying to tone up. It was difficult to gain muscle, being made of mostly _fire,_ but he finally figured out how to do it.

Suddenly Gaster shook his head, realizing he’d been staring like a horny moron. “…You look nice.” He commented, his face blushing slightly.

Grillby couldn’t help but laugh. “You’re too cute.” He said. “Now _you_ need to get out of your shirt.” Gaster pulled from the bottom, taking off the heavy knit sweater. Now with his arms, ribcage and part of his spine completely exposed, it was Grillby’s turn to ogle his partner. “Pants too.” He commanded. Gaster fumbled with his belt for a moment, but once he got it off, Grillby took it out of his hands. He had an idea for that belt and placed it on the edge of the bed. Lastly, Gaster took off his pants, tossing them on the floor wherever they may land.

Grillby grinned, gently pushing Gaster onto his back. He crawled on top of him, radiating a comforting heat into Gaster’s bones. Grillby gently stroked the side of Gaster’s cheekbone, eliciting a shiver from the skeleton beneath him. “Are you alright?” He asked.

“Yes,” Gaster answered. He shifted on the bed, grabbing Grillby’s arm with one hand. “Come on, let’s get on with it.” Gaster said impatiently.

Grillby laughed and pressed his mouth against Gaster’s skull. He kissed his forehead, trailing more kisses down the cheekbones. Relaxing into the sensations, Gaster closed his eyes. Grillby moved lower, planting kisses under the curve of Gaster’s jaw, then his neck.

“Mmmhmm.” Gaster hummed.

“You like that?” Grillby asked.

“Yes…” He answered.

Grillby took that as an invitation to continue. He moved both hands to gently fondle Gaster’s ribcage. He stroked and caressed each bone, kissing the clavicles. But that wasn’t enough. Grillby had an idea. Cautiously, he licked the underside of the bone. Gaster lurched forward, grabbing Grillby’s arms with both hands.

“Oh shit, I’m sorry-“ Grillby stuttered, moving away.

“N-no, it felt good. I like it.” Gaster said reassuringly.

“Oh, okay.” Grillby bent back down, licking the rib once more. Gaster arched his back, curling up at the feeling. It was _so_ good.

“Hnnng.” He whimpered. Grillby began to fondle Gaster’s pelvis, while still licking each individual rib. A pool of dark-blue magic began to coalesce in Gaster’s pelvis. Grillby couldn’t wait to be inside him. Gaster spread his legs, enticing the fire elemental to go further.

Grillby continued his ministrations, but instead he focused on licking Gaster’s pelvis. Starting from the iliac crest, he moved lower and lower to the pubis in the center. Gaster mewled softly at every touch, getting more and more aroused with every stroke. His magic had formed a ready and willing entrance for Grillby.

Grillby licked the magic entrance, swiping his tongue along the wet folds over and over. Gaster reached back, grasping the pillows behind him with both hands. Grillby paused for a moment and stuck two fingers inside the magic, scissoring them slightly. “AAHH.” Gaster nearly screamed. The sudden penetration had him arching his body almost completely off the bed, but Grillby pushed him back down.

Continuing to work his fingers inside Gaster’s entrance, he moved to undo the button and zipper on his own pants. He pulled them down just enough to let his erection spring free. Gaster let out a needy whine at the sight of Grillby’s cock. He raised his hips up and down, in rhythm with the thrusting of Grillby’s fingers. “Mmm…come on, hurry up.” Gaster said with a moan.

Grillby grabbed his cock, stroking it up and down a few times. He hadn’t realized that doting on Gaster had made him this hard already. But he wasn’t ready to fuck Gaster _just_ yet. Grillby extended his arm, groping on the bed for that belt he laid down earlier. Finally, he took it in hand. “Gaster, would it be alright if I tied up your hands with this?” He asked. Gaster nodded emphatically. His lust-fueled brain wasn’t capable of forming _sentences_.

With permission, Grillby grabbed both of Gaster’s slender wrists, binding them together with the belt. He tied them up with a sturdy knot, and guided Gaster’s arms to rest on either side of his head. Then Grillby pumped himself a few more times and pressed the tip of his cock inside of Gaster.

“Ah, _fuck_ ” Grillby said with a groan. Gaster’s entrance was perfectly tight and wet. Clenching down on him, even though he was only half-way in. Grillby pushed in slowly, finally sheathing himself all the way. Gaster’s eyes were screwed shut, body trembling with want.

“Please…move…” He whimpered. Grillby wasted no time after hearing that request. He picked Gaster up by his hips, pulling out almost completely, then slamming back in. “Yes, yes!” Gaster cried.

Grillby thrust harder and harder, working into a steady rhythm. He couldn’t stop moving, getting closer and closer to finishing. Gaster fell limp, like a rag doll. He spread his legs further, prompting Grillby to go deeper with every stroke.

It didn’t take long for them to get close to climax. Gaster came first, with a few grunts and loud whine. Grillby sped up, chasing his own orgasm. _“Fuck…ugh, Gaster.”_ He growled. _“Fuck, fuck, fuck-ahhh!”_ Then he came too, filling Gaster’s hole with cum. “O-oh shit, sorry I didn’t mean to-“ Grillby stammered.

Gaster shook his head and laughed. “It’s okay…I don’t care.” He said sincerely. Grillby let out a sigh of relief and collapsed on top of the skeleton, thoroughly spent. The two monsters laid there for a few minutes, just basking in the sweet warmth of their afterglow. Grillby reached up again and kissed Gaster’s forehead tenderly. The heat of Grillby’s body pierced through Gaster’s bones, warming him and relaxing all his tension like a living, breathing hot-pad.

“Grillbert, can you untie me now? My wrists are starting to hurt.” Gaster said. Grillby pushed himself up with both hands, then straddling Gaster’s waist, he undid the knot in the belt, letting the boney arms go free.

“There you go.” He said with a grin. Gaster closed his eyes, sighing happily.

“Gaster, will your boys be alright if you…if you spend the night here with me?” Grillby asked hesitantly. He didn’t normally ask Gaster to stay after they had sex, especially since he had two kids to look after…Tonight though, he really wanted Gaster to linger a little longer. And to his surprise, Gaster said yes.

“I predict they’ll pass out on the couch,” he replied “With their bellies stuffed full of popcorn, around midnight or so. They’ll be fine.” Grillby beamed, a tiny ripple of flame flying off his head. He laid down beside Gaster, wrapping his arms around the slender skeleton.

“I want to ask you something else too, Gaster.” He murmured.

“Hmm? What?” Gaster turned his head, so he could gaze at Grillby’s face. His beautiful, now-blushing face.

“Uh, well…” Grillby said nervously. “You know we’ve been dating for a year now…and uh…” He trailed off. No, this was getting too awkward already! Grillby mentally cursed himself. “And uh, I’ve already told you a few times how much I love you, Gaster…and I was wondering if uh…” _“Ah fuck it! I’m gonna get that box out of the dresser._ ” Grillby thought.

Suddenly, he leapt out of the bed, and walked over to his dresser. He fumbled around the top drawer, sifting through his socks, until he found _it._ He palmed the small, velveteen box, and returned to the bed. Gaster leaned on his arm, staring curiously at the fire monster. “I was wondering…if you would like to marry me?” Grillby said, popping open the box with a flourish. Inside it laid a simple gold ring, one he’d managed to pawn off the Temmies a month or so ago.

Gaster’s hand flew to his mouth in shock. His eyes widened, and his brain went numb. _Oh stars_ …What should he say?!

Grillby, to his credit, didn’t show any signs of nervousness while he waited for Gaster’s answer. But inwardly, he was terrified. _“Ahh…I should’ve waited for another time…This was stupid, you don’t fuck someone then ask them to marry you._ ” He thought.

With a rustle of bedsheets and a creek from the bed, Gaster stood up in front of Grillby. He was only a couple of inches shorter than the fire elemental, but he felt so small. Gaster still remembered, that night at the end of their very first date, Grillby had kissed him in the snow, underneath the ambient glow of the Snowdin lights. What a beautiful night that was.

“Grillbert,” Gaster began, “That’s extremely sweet of you but-“ Gaster turned away, collecting his thoughts. “I’m afraid I’m not really marriage material…I mean, I drink and smoke, I’m always working on some project or other at the Lab, so I’m hardly ever at home, and I have two sons…”

In Gaster’s mind, his lifestyle and personality were only applicable to boyfriend status; someone to talk to, to cuddle, and to fuck with. “I just…I don’t want you or your daughter to get involved so deeply that you get hurt when I’m not around. It pains me enough to stay away from the boys all the time.”

Grillby’s heart sank, he didn’t want to listen to this-he couldn’t stand this. But he stood there anyways, eyes transfixed on Gaster’s form, wishing with all his might. “Gaster, I don’t care that you’re busy with work a lot. I am too. And as for Fuku, she’s getting older-spends most of her time in Hotland anyway…I could look after your boys, and we could-“ Gaster shook his head violently.

“No, no.” He said flapping his hands. Grillby knew he did that whenever he was overwhelmed or stressed. “I can’t marry you Grillby…you wouldn’t be happy with me as your spouse.” Gaster insisted.

Grillby’s flames died down, a natural reaction he had to whenever something upset him. He grabbed Gaster’s arm, pulling him close “Are you saying that because you think you’re helping me, or because you’re scared?” He asked. Gaster shrugged.

“Both.” He admitted.

Grillby sighed. Usually Gaster didn’t relent that kind of information easily…Maybe it was because he was tired. “What are you scared of?” He asked, genuinely concerned. Perhaps if he knew what Gaster was afraid of, then he could relieve some of those fears.

“I-I…” Stuttered Gaster. “You’ve been married before-to Fuku’s mother…I haven’t. I’ve never been married before. I can’t compete.” Gaster said, wrenching his arm free. He walked over to the other side of the bed, retrieving his pants from the floor. Gaster stepped into them, doing a little hop to get them up to his pelvis correctly. He took the belt off the bed and slid it through the pant loops, before buckling it.

“Gaster, Menorah died 6 years ago.” Grillby hissed. “And while I do miss her from time to time, I’ve moved on.” Gaster didn’t respond. “I want to marry _you_ now, and you don’t have to compete with anyone, I promise.” Still, the skeleton said nothing. He went to the foot of the bed, finding his discarded sweater and putting it on as well. “Why are you getting dressed? I thought you were staying over?” Grillby asked, his tone bordering on aggressive.

“I changed my mind.”

Grillby wasn’t buying it. “No, you just don’t want to stay here and talk to me.” He said.

Gaster huffed, crossing his arms. “Where are my glasses? I need to go.”

“No, not until you talk to me.” Grillby stubbornly refused.

“I’m not going to say yes! I can’t marry you.” Gaster pleaded. He needed Grillby to realize this. Otherwise, they’d be in a stalemate forever.

“But _I don’t care_ about whatever insecurities you might have, Gaster. I _love_ you damnit, and I would never compare you to Menorah, or make you feel uncomfortable.” Grillby replied in earnest. His tone changed from angry to desperate. The velvet box slipped out of his hand and the ring landed with a _plink_ on the floor. “Ugh.” He groaned.

Gaster finally found his glasses on the nightstand next to Grillby’s bed. He put them on, blinking as his eyes readjusted to them. Then he headed towards the door. “Hey! Gaster!” Grillby dashed to the door, blocking his exit.

“Grillby what is your problem?! I told you no. Take the fucking answer!” Gaster yelled. Then a sudden sort of screaming match erupted between the pair.

“What’s the real reason you can’t marry me?”

“You don’t want to know that!”

“Tell me!”

But as soon as it started, the match ended. Gaster sighed, hanging his head. He grew quiet and still…unable to move. “I can’t marry you, because there’s already someone else out there that I want to be with…And I can’t lie to you-I can’t be your husband when I _really_ want to be someone else’s.” Now the ugly truth was out. Gaster wished he could crawl under a rock somewhere and hide for 141,538 years.

“I-I…see.” Grillby replied somberly. “Then…if you really love someone else, then why aren’t you with _them?_ ” He asked. Gaster stared down at the floor, wringing his hands.

“Because, the one I love is already taken…by Lady Toriel.” Suddenly Grillby realized.

_“Oh…oh stars.”_ He thought.

“I have loved Asgore since I was 12 years old, back when it was nothing more than a school-boy’s crush.” Gaster confessed. “And while I love being with you, I don’t want to marry you when my deepest feelings are for someone else.”

“But Gaster, Asgore is a married man. You’ll _never_ be able to have him, and if you pine after him forever, you’ll always be miserable!”

Gaster shrugged. “You think I don’t know that? That’s why I’ve never dated. I’ve never been married. I’m almost 40 fucking years old and never had the guts to tie the knot with someone….And sure it’s partially due to my busy work schedule, but I can’t bear to have a dishonest relationship like that.”

“Then why me? Why drag me through this if you never intended to return my feelings?” Grillby retorted. His fists shook with rage. He was _hurt. “How dare he waste a year of my fucking life if he-“_

“I didn’t mean to. But as I recall, _you_ latched onto _me._ ” Gaster snipped, de-railing Grillby’s train of thought. “You asked _me_ out, fucked me twice and said _you_ loved me.” “ _I_ told you I wasn’t looking for anything serious, and _you’re_ the one with the ring.” Gaster scolded. Grillby couldn’t take it anymore.

“Get out. Get out of my bar. We’re done.” He stepped aside, giving Gaster access to the door. The skeleton came to the door and picked up his shoes.

“It was good while it lasted.” Gaster said.

_“Get out.”_ Grillby was seething by this point.

Gaster closed his eyes, letting out a shaky breath. He slipped on his shoes, then descended downstairs without another word.


End file.
